In the 19th century, in addition to those migrating to various parts of the world,
many Grenfells moved out of Cornwall to other mining areas of England, Scotland
and particularly Wales, and to the business and banking centres in London.
This resulted in the percentage of Grenfells living in Cornwall falling from 86% in 1841 to 53% in 1901.

In terms of frequency of the name, in the 1881 census there were 578 Grenfells recorded which represented 0.00223% of the population or 1 in 44,931.
An Office for National Statistics database for the year 2002 recorded 750 Grenfells equal to 0.00138% of the population, a frequency of 1 in 72,533. This shows a considerable reduction as a percentage of the population as a whole. The name was ranked =8835.